This invention relates to a grommet for a shielded cable.
A related camera module, which is an example of structural bodies using a shielded cable, will be described with reference to FIGS. 7 and 8. The camera module 51 includes a camera module body 52, a module receiving case 53, and a shielded cable assembly 54. The camera module 51 is, for example, an on-vehicle one (see, for example, JP-A-2002-270313).
The camera module body 52 includes a CCD camera 56 having a lens 55, and a board 57 on which the CCD camera 56 is mounted. The CCD camera 56 includes a body fixed to one side (or surface) of the board 57 such that the lens 55 projects from the other side (or surface) of the board 57. A circuit of a predetermined pattern is formed on the one side of the board 57, and the body of the CCD camera 56 is electrically connected to this circuit. A connector 58 (through which the transmitting of signals to the exterior, the supply of electric power, etc., are effected) is provided at the circuit. The camera module body 52 is adapted to be fixed to an upper open side of the module receiving case 53 by screws.
The module receiving case 53 has an internal space for receiving the body of the CCD camera 56, etc. A through hole is formed through one side wall of the module receiving case 53, the interior and exterior of the module receiving case 53 communicating with each other through this through hole. Although this through hole is not shown in the drawings, the shielded cable assembly 54 is mounted on the module receiving case 53 through this through hole.
As shown in FIGS. 7 and 8, the shielded cable assembly 54 includes a shielded cable 59, a connector 60, and a module mounting portion 61. The shielded cable 59 includes a plurality of insulated conductors 62, a shielding braid 63 provided around the plurality of insulated conductors 62, and a sheath 64 provided around the braid 63. The shielded cable 59 has been subjected to end processing as shown in the drawings.
With respect to this end processing, the plurality of insulated conductors 62 are led out from the front side of the module mounting portion 61, and the connector 60 is provided at distal ends of the thus led-out insulated conductors 62. The connector 60 includes a connector housing 66, and terminals 65, connected respectively to the distal ends of the insulated conductors 62, are inserted into the connector housing 66, and are fixed thereto.
The module mounting portion 61 includes a mounting member 67, and an O-ring 68. A processed portion of the shielded cable 59 (at which the sheath 64 is removed from the insulated cable 59) is received within the mounting member 67, and this portion is sealed by potting 69.
In the above construction, the shielded cable assembly 54 is mounted on the module receiving case 53 by threading a threaded portion 70, formed on the mounting member 67 of the module mounting portion 61, into the through hole formed in the module receiving case 53. When the shield cable assembly 54 is mounted on the module receiving case 53, the O-ring 68 is compressed between the mounting member 67 and the module receiving case 53 to achieve a waterproof performance. The connector 60 of the shielded cable assembly 54 is connected to the connector 58 of the camera module body 52.
With respect to the waterproof performance, the intrusion of water along the shielded cable 59 is suppressed by the potting 69. Also, the intrusion of water is suppressed by the O-ring 68. Further, thanks to the provision of the potting 69, a residual uncut portion of the braid 63 (The braid includes wires woven obliquely with respect to the axis of the cable, and therefore when the braid is cut, this cut end tends to project.), projecting from a cut end of the sheath 64, will not be exposed to the interior of the module receiving case 53. As a result, the short-circuiting between the braid and the camera module body 52 is prevented.
Incidentally, the module mounting portion 61 of the shielded cable assembly 54 involves considerable material and processing costs, considerable time and labor for its assembling operation, etc., and therefore there has been encountered a problem that the overall cost of this assembly 54 increases. If it is only necessary to cover the processed portion of the shielded cable 59 in order that the residual uncut portion of the braid 63 will not project, the use of a known heat-shrinkable tube 71 as shown in FIG. 9 can be proposed as an alternative measure. In FIG. 9, reference numeral 72 denotes a shielded cable, reference numeral 73 denotes a residual uncut portion of a braid, and reference numeral 74 denotes a connector connected to distal ends of insulated conductors 75.
However, this alternative proposal, using the heat-shrinkable tube 71, is of such a structure that it is difficult to mount a seal member such as the O-ring 68, and therefore there is encountered a problem that a sufficient waterproof seal can not be secured between the shielded cable and the module receiving case. And besides, in the alternative proposal using the heat-shrinkable tube 71, the shielded cable 72 is made stiff by the rigidity of the shrunk tube 71, which results in a problem that the efficiency of a cable-installing operation is lowered.
Other alternative proposal than the heat-shrinkable tube 71 which is inexpensive, and can easily secure a sufficient sealing performance is, for example, a structure as shown FIGS. 10 and 11. This structure will be briefly described below.
In FIGS. 10 and 11, this structure includes a module receiving case 78 comprising an upper case 76 and a lower case 77, a rubber plug 80 mounted in a mounting recess 79 formed in the lower case 77 of the module receiving case 78, and a cable 81 passing through the rubber plug 80 (see, for example, JP-UM-B-6-11564). The rubber plug 80 includes a tube 82 for intimate contact with an outer peripheral surface of the cable 81, a bellows portion 83 extending continuously from this tube 82, and a thickened peripheral wall portion 84 which is continuous with the bellows portion 83, and is mounted in the mounting recess 79.
Here, when thinking about the case of applying a shielded cable assembly with a rubber plug to a camera module, using the above structure for reference, such a structure for example as shown in FIG. 12 can be proposed. In FIG. 12, reference numeral 85 denotes a camera module body, reference numeral 86 denotes a module receiving case, and reference numeral 87 denotes the shielded cable assembly with the rubber plug 88.
The camera module body 85 is received in the module receiving case 86. A connector 90 of the shielded cable assembly 87 is connected to a connector 89 of the camera module body 85 received in the module receiving case 86. In the shielded cable assembly 87, an end portion of a shielded cable 91 is processed, and a plurality of insulated conductors 94 are led out from a region where a sheath 92 and a braid 93 are removed from the shielded cable, and the connector 90 is provided at distal ends of the thus led-out insulated conductors 94. The rubber plug 88 is mounted on the processed portion of the shielded cable 91, and is adapted to be mounted on a mounting portion 95 of the module receiving case 86.
The shielded cable assembly 87, shown in FIG. 12, has the rubber plug 88, and therefore has the following problems. Namely, when an end processing operation is to be applied to the shielded cable 91 which is beforehand passed through the rubber plug 88, this processing operation is effected after the rubber plug 88 is moved to a position where this rubber plug will not interfere with the processing operation, and after this processing operation, the rubber plug 88 is returned to a predetermined position. Therefore, there is encountered a problem that the efficiency of the operation is low.
And besides, since the rubber plug 88 must be moved, the shielded cable 91 need to have an extra length portion 96. Therefore, there is encountered a problem that this structure has an influence on the cost and a receiving space. Furthermore, when the rubber plug 88 is not completely returned to the predetermined position, a residual uncut portion of the braid 93 projects toward the camera module body 85 as shown in FIG. 12. Therefore, there is a problem that the short-circuiting, as well as damage of the insulated conductors 94, can occur.
Incidentally, when the rubber plug 88 is so modified as to cover the residual uncut portion of the braid 93 in order to prevent the projecting of this residual uncut portion, that portion of the rubber plug for intimate contact with the shielded cable 91 is reduced in size in the case of the illustrated structure, and this invites a problem that the sealing performance and a holding force can be adversely affected. There is a further problem that depending on the manner of receiving the extra length portion 96, the processed portion of the shielded cable 91 is pushed out by a restoring force of the bent extra length portion 96, so that the residual uncut portion of the braid 93 projects.